Attempts to extract early biomarkers and expedite detection of Autism Spectrum Disorder (ASD) have been centered on postnatal measures of babies at familial risk. Here, we suggest that it might be possible to do these tasks already at birth relying on ultrasound and biological measurements routinely collected from pregnant mothers and fetuses during gestation and birth. We performed a gradient boosting decision tree classification analysis in parallel with statistical tests on a population of babies with typical development or later diagnosed with ASD. By focusing on minimization of the false positive rate, the cross-validated specificity of the classifier reached to 96% with a sensitivity of 41% and a positive predictive value of 77%. Extracted biomarkers included sex, maternal familial history of auto-immune diseases, maternal immunization to CMV, IgG CMV level, timing of fetal rotation on head, femoral length in the 3rd trimester, white cells in the 3rd trimester, fetal heart rate during labour, newborn feeding and newborn’s temperature difference between birth and one day after. Statistical models revealed that 38% of babies later diagnosed with ASD had significantly larger fetal cephalic perimeter than age matched neurotypical babies, suggesting an in-utero origin of the bigger brains of toddlers with ASD. Results pave the way to use pregnancy follow-up measurements to provide an early prognosis of ASD and implement pre-symptomatic behavioral interventions to attenuate efficiently ASD developmental sequels.Competing Interest StatementDr. S. Alain reported being a Scientific Expert for GSK, Shire, Sanofi, MSD, Merck, Biotest, BioMerieux and Hologic, and IP France Solstice study (Takeda). Dr. Y. Ben-Ari reported being the CEO and shareholder of BA Biomedical, a company dedicated to the use of artificial intelligence in biomedical research, and Neurochlore, a company dedicated to treat autism. He is also the president of the IBEN foundation, a non-for-profit foundation dedicated to study the early pathogenesis of brain disorders. Dr. S. Hantz reported receiving a congress fee, travel and accommodation by MSD vaccines, a congress fee from Diasorin, and a remuneration as speaker for "Expert days in virology" from Roche Diagnostics. Dr. E. Lemonnier reported being a shareholder of Neurochlore. Dr. H. Rabiei reported his salary paid by Neurochlore. No other disclosures were reported.View Full Text